Multi-material spray gun, spray coating system and method of quickly changing the material being sprayed

ABSTRACT

A multimaterial spray gun characterized by its ability to quickly change from one material to another by spraying through a single nozzle which includes a body having n chambers each adapted to receive respective different ones of n preselected materials, a common discharge nozzle having a spray passage therethrough, means coupling the spray passage to each of the n chambers and valves for selectively opening and closing the coupling means, a spray coating system using the spray gun wherein the material being sprayed utilizes a part of the system while another portion of the system is simultaneously being flushed to remove the previously sprayed material and a method for quickly changing from one material being sprayed to another.

United States Patent 1 3,558,051

[72] Inventors Jay H. Strickler 2,645,379 7/1953 Audia 222/148X Shaker Heights; 2,650,003 8/1953 Coleman 222/318 Richard C. Watson, Mayt'ield Heights, Ohio 3,009,653 1 1/ 1961 Hedeman 239/416.1X

[21] Appl. No. 680,183 3,310,204 3/1967 Zinman et al. 239/305X [22] Filed Nov. 2, 1967 2,762,652 9/1956 Carter 239/536X [45] Patented Jan. 26, 1971 3,067,987 12/1962 Ballon et a1... 222/145X [73] Assignee Inland Steel Company 3,306,495 2/1967 Wabers 222/145X Chicago, 111.

a corporation of Delaware [54] MULTI-MATERIAL SPRAY GUN, SPRAY COATING SYSTEM AND METHOD OF QUICKLY CHANGING THE MATERIAL BEING SPRAYED Primary Examiner-Robert B. Reeves Assistant Examiner-Norman L. Stack, Jr. AttorneyWolfe, Hubbard, Leydig, Voit and Osann ABSTRACT: A multimaterial spray gun characterized by its ability to quickly change from one material to another by spraying through a single nozzle which includes a body having n chambers each adapted to receive respective different ones of n preselected materials, a common discharge nozzle having a spray passage therethrough, means coupling the spray passage to each of the n chambers and valves for selectively opening and closing the coupling means, a spray coating system using the spray gun wherein the material being sprayed [56] References Cited utilizes a part of the system while another portion of the UNITED STATES PATENTS system is simultaneously being flushed to remove the previ- 2,112,546 3/1938 Smart 239/305X ously sprayed material and a method for quickly changing 2,232,772 2/1941 Crowley et al 239/412 fromone material beingsprayed to another.

If? //V All/fill #4716174 1 W2 7 w ,1 if .7! /II if /1) l! s f I J! I! f I ,7 a, )2 31 as I! 70 I! /a PATENTEU JAN26 1971 SHEET 2 OF 2 MULTI-MATERIAL SPRAY GUN, SPRAY COATING SYSTEM AND METHOD OF QUICKLY CHANGING THE MATERIAL BEING SPRAYEI) The present invention relates generally to spray-coating methods and apparatus and, more particularly to particularly, to spray guns and spray-coating systems for coating the surfaces of workpieces such as, merely by way of example, containers, cylindrical shells or the like. In its principal aspects the present invention is concerned with improved spray-coating methods and apparatus employing one or more novel spray guns which are characterized by their ability to permit rapid changeover or replacement of any given material (such as paint, lacquer, rust inhibitor or other material in a liquid or semiliquid state) that is being used to coat the workpiece to a different material or to a different color, yet without requiring any significant interruptions or downtime of the equipment and personnel.

In various industries such as, for example, the container manufacturing industry, efforts have been made to apply coatings of particular materials to containers or similar products on a mass production basis. One particularly troublesome obstacle to achieving a sufficient speed for mass production has been the replacing or changing of the material that is being sprayed by another material or by the same material but a different color. The coating and painting requirements of a workpiece such as a container makes it necessaryto periodically change the material to, for example, a different color. Since commercially available spray coating equipment is capable of coating about 500 to 600 containers per hour (55 gallon size), any significant interruptions that repeatedly occur will correspondingly diminish the number of containers that can be coated in any given period of time. A byproduct of any such interruptions will be the idling of all personnel associated with the mass production of the completed coated containers. In a typical situation, this could involve as many as 60 men.

To accomplish the changing or replacing of a material as now practiced it is necessary to exhaust the material remaining in the system. While some systems provide for directing the material to a reservoir where at least a portion of the material can be reclaimed, the material is generally flushed from the spray-coating system by passing a solvent therethrough and allowing the solvent and material to be sprayed into the spray booth in which the workpieces are coated. After the material being replaced has been flushed from the system, the conduits connecting the material reservoir to the pump or other means supplying the material to the spray gun are placed in the new material reservoir. The system is then primed by passing the new material therethrough. The system is ready to coat the containers or other workpieces as soon as the new material being sprayed is substantially devoid of any residual solvent and replaced material.

The lapse of time associated with the replacing of one material by another can be a minimum of about 3 minutes but will often extend to upwards of minutes or more when a spray-coating system including a plurality of guns is involved.

The use of another spray gun together with the necessary pumps, valving and conduits when a material or color change is required is not a suitable alternative to eliminate the interruptions described above. Coating techniques require a precision that could not be accomplished by two separate guns in a side-by-side relationship. To employ another spray gun when a material or color change is required it would be necessary to move the gun in use out of position and set the other gun in the identical position of the first gun so that the area being coated would not change.

It is a general aim of the present invention to provide a novel spray gun and improved spray-coating methods and apparatus utilizing such spray guns which are characterized by their ability to allow a changeover from one material to another or from one color to another without any significant interruptions. A related aspect of this invention is to provide a spray gun and spray-coating methods and apparatus in which a new material or color which is to be introduced can replace the material then being sprayed and then be sprayed onto the workpiece within seconds.

A more specific object of the invention is the provision of an improved unitary spray gun characterized by its compactness, lightness in weight, and by its need for only minimum space requirements, yet which is capable of spraying n different materials or different colored materials (where n equals to two or more) from a single nozzle, and which is also capable of rapid changeover from material to material or color to color with substantially no downtime of the equipment or its operating personnel. In this connection it is an object of the invention to provide an improved spray gun apparatus of the foregoing type which permits one material to be sprayed during a spray-coating operation utilizing a part of the apparatus while another portion of the apparatus is simultaneously being flushed to remove the previously sprayed material.

In accordance with another of the aspects of the present invention it is an object to provide a novel spray gun and spraycoating methods and apparatus for coating workpieces which decreases the maintenance problems associated with the spray booth in which the workpieces are coated.

Other objects and advantages of the present invention will become apparent as the following description proceeds, taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a top plan view of a spray gun made in accordance with this invention which allows a changeover from one material to another or from one color to another without any significant interruptions;

FIG. 2 is a cross-sectional view tan taken substantially along the lines 2-2 of FIG. 1;

FIG. 3 is a schematic view illustrating a spray-coating system using the spray gun illustrated in FIGS. 1 and 2; and

FIG. 4 is a schematic view illustrating the use of a plurality of the spray guns illustrated in FIGS. 1 and 2 in a spray-coating system that is adequate to carry out the coating of a container.

While the invention is susceptible of various modifications and alternative forms, specific embodiments thereof have been shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that is it is not intended to limit the invention to the particular forms disclosed, but, on the contrary, the intention is to cover all modifications, equivalents and alternatives falling within the spirit and scope of the invention as expressed in the appended claims. For example, the exemplary embodiment that will hereinafter be described includes a novel spray gun that is generally used where only two different materials or colors will normally be employed. It should, however, be understood that the present invention can be employed to spray as many different materials as desired or alternatively as many different colors of the same material as desired. Moreover, while the novel spray gun is advantageously used in connection with automated spray-coating systems, similar advantages are derived when the spray gun is used as a hand gun.

In the exemplary embodiment of the spray gun illustrated in FIGS. 1 and 2, the gun 10 includes a body 12 comprising two detachable portions 14, I6. The forward portion 14 is adapted to receive the sources of material that are to be sprayed and includes suitable fittings for coupling the sources of material with the body 12. The rear portion 16 includes suitable valving and activators therefor for selecting the particular material that is to be sprayed. The two portions can be connected together in any suitable manner such, for example, as bolts 18. While the body 12 could be integrally formed, it is preferred to form it in two portions because of the easier machining and the easier replacement of wornout parts.

To serve as the reservoirs through which the material to be sprayed passes the forward portion 14 of the body 12 is formed with a plurality of n chambers 20, two such chambers being illustrated. The chambers 20 are each provided with a material inlet 22 and outlet 24, the terminal positions of which are screw-threaded as indicated at 26 and 28, thus enabling the gun chambers to be coupled to respective different ones of n material supply sources 30 and 32 (FIG. 3) through material supply lines 34 and 36. The materials can be returned from the respective ones of the n chambers to a return reservoir or reservoirs. As here shown, the materials pass via return lines 38 and 40 to the respective ones of the n material supply sources which serve as the return reservoirs so the system essentially recycles the materials that are not being sprayed. The supply and return lines are each connected to the respective ones of the n chambers through high pressure fittings 42 that are screwed into the terminal portions of the various material inlets and outlets.

A common discharge chamber through which the particular material being sprayed must pass is suitably provided. In the illustrative embodiments the common discharge chamber 44 is formed in the forward portion 34 of the body I2. While it is preferred for purposes of uniform flow of the material being sprayed to form the common discharge chamber as in the illustrated embodiment, those skilled in the art will appreciate that it need only be large enough to serve as a common chamber through which material from any of the n chambers 20 must pass and could be formed immediately adjacent the spray passage of the single nozzle of the gun. Connecting the n chambers 20 with the common discharge chamber 44 are passageways 46.

In accordance with one aspect of the present invention n different materials or different colored materials are sprayed through a single nozzle. To this end there is provided a spray nonle 48 having an orifice 50. The spray nozzle 48 terminates in a flange 52 and a threaded collar 54 holds the spray nozzle 48 in position by maintaining the flange 52 adjacent the end 56 of the forward portion I4 of the body I2. To prevent the orifice 50 from becoming blocked, a conventional filter can be used. As shown in FIG. 2, a filter 58 having a terminal flange 60 is positioned in the spray nozzle 4 8. It is held in position by reason of the clamping action exerted on its flange 60 by the flange 52 of the spray nozzle 48 and the end 56 of the forward portion l4.

To allow a selected one or ones of the n chambers 20 to be opened and closed and a particular material or color to be sprayed suitable valving is employed. Thus, valves 62 and 64 are provided for connecting the interior of respective ones of the n chambers 20 with the common discharge chamber 44 through the passageways 46. The illustrated valving, 62, 64, comprises two needle valves each having a stem 66 and a seat 68. The end of the stems 66 are provided with a rigidly attached piston 70. The n chambers 20 are each formed with an open end into which are positioned threaded inserts 72 which hold the seats 68 in position. Packings 74 provide seals for the chambers and in turn are held in position by collars 76 that are screwed onto the threaded inserts 72.

Provision is also made for selectively activating the valves 62 and 64 so as to close any open passages and to selectively open another passage or passages. To a achieve this end the rear portion 16 of the gun body 12 includes n sets of concentric bores 78, 80, one set of which is in alignment with one of n chambers 20. Each set of the bores forms a shoulder 82 against which the piston 70 rests. The bores 78 are of sufficient size to allow the pistons to be slidably positioned therein. Springs 84 bias the pistons 70 against the shoulders 82 and the stems 66 to a seated position. Threaded members 86 are located on the threaded terminal ends 88 of the rear portion 16. To unseat the needle valves each of the bores 80 are provided with air inlets 90 having threaded portions 92 to receive pressure fittings 94. Introduction of air (or other suitable pressure fluid) from a source which is not shown but can be the same as that shown in FIG. 3, causes the piston 70 to move rearward thereby unseating the stem 66. Packings 96 seal the bores 80 from a cavity 98 which is formed in the rear portion 16 of the gun body 12. The cavity allows easy access to the threaded inserts 72 and can be provided with a cover plate 100 connected to the gun body 12 by screws I02 to prevent the entrance of foreign particles.

Turning to FIG. 3 there is diagrammatically illustrated a spray-coating system utilizing the gun hereinbefore described.

To transport the material from the material sources 30 and 32 to the spray gun 10 under pressure there are provided pumps 110. Any conventional pumps capable of forwarding the material under the l,500 to 3,000 pounds per square inch pressure necessary for airless spraying techniques can be used. The motive force for the pumps can be a source of compressed air connected to the pumps 1 10 by conduits I12 and I14. Regulation of the air pressure is provided by conventional sets of regulator valves II6, I18 interposed in conduits 112 and I14. Valves 120 are positioned in lines 34 and 36 to provide on-off flow control from respective ones of the n chambers 20 to the orifice 50. Similarly, valves 122 are included in return lines 38 and 40 to provide adjustable orifices in the return lines as necessary to maintain the pressure required for spraying through the nozzle 48.

While the invention has been described with respect to airless spraying techniques, it should be appreciated that the invention is similarly applicable to gas-atomizing techniques wherein the material being sprayed is broken up by impingement with a stream of gas. The contact between the fluid and the gas may take place entirely outside the nozzle or within a chamber from which the spray exits through an orifice. With this type of spray system the pressure required to deliver the material being sprayed may be on the order of 100 pounds per square inch or less, as contrasted with the pressures of 1,500 to 3,000 psi. normally utilized with airless spraying techniques.

One particularly advantageous utility of the spray gun of this invention is in conjunction with the coating of containers on a mass production basis. To this end, as shown in FIG. 4, a plurality of the spray guns 10 can be positioned in a particular manner to spray a cylindrical container that is rotated about its axial central axis by means not shown. The illustrative system employs I1 guns spatially arranged about the container 130. As is well known in the art timers could be employed to program the spray cycle that is necessary to satisfactorily coat a container, remove it from the spray booth and put another container in position.

Considering the operation of the illustrative system, the materials to be sprayed are transported to the n chambers 20 of the gun body 12 by pumps 110. At any given time when a container or other workpiece is being sprayed, at least one of the needle valves has its stem 66 unseated due to air or another medium having forced the piston 70 rearward. The material being pumped through, for example, supply line 34 thus passes through the passageway 46, the common discharge chamber 44 and the orifice 50 whereupon the stream of material atomizes upon contact with the air. To change from the material or color being sprayed to the material source or color 32 it is only necessary to cut off the flow of air to the one bore and supply air to another selected bore 80. Further spraying of the material ceases since the stem assumes a seated position due to the biasing of the spring 84. At the same time the material flowing through the supply line 38 is allowed to exit from the gun through the orifice 50 in the same manner as described above. A workpiece can be moved into position and coated after the replaced material is blown out of the system by the new material being used. This changeover is complete within a few seconds. The supply line 34, return line 38 and other portions of the system can then be flushed out with solvent by replacing the material supply sources 32 with a solvent source and pumping the solvent through the system. The next material or color that is needed is then moved into position to be pumped when still another changeover is required.

While the exemplary embodiment has two chambers this in vention is equally applicable to spray guns with n number of chambers, n being an integer greater than one. When there are n chambers, there will be n passages and, generally n sources of materials to be sprayed. It should also be appreciated that this invention is applicable to various types of changeovers that are required. For example, a change of materials not only includes replacing a material such as, for example, paint with a lacquer but also includes any situation wherein it would have heretofore been necessary to employ two spray guns such as the replacement of red paint by blue paint. Similarly, while the new material is perhaps generally used to coat a different workpiece from the one coated by the replaced material, it is within the scope of this invention to sequentially coat the same product with a plurality of materials. This could be, for example, the spraying of a container with lacquer after having been painted by the same chamber of the spray gun.

Thus, as has been seen the present invention provides a novel spray gun which allows one material to be quickly replaced with another material. This is accomplished by an improved unitary spray gun that is capable of spraying n different materials from a single nozzle. While one material is being sprayed the apparatus associated with the material that was replaced can be simultaneously flushed to ready the spray gun for the spraying of still another different material. The spray gun of this invention is also characterized by its com pactness and lightness in weight.

We claim: a

1. In a multimaterial spray gun for use with n sources containing respective different ones of n materials, the combination comprising, a body including a forward portion and a rear portion with a cavity defined therebetween, said forward portion having n chambers, means including an inlet and an outlet port in said forward portion leading to each of said chambers for connecting said chambers with respective ones of said sources so that said chambers receive a substantially continuous circulating stream of respective different ones of said it preselected materials therethrough, a common discharge nozzle in said forward portion having a spray chamber therethrough, passage means leading to said spray chamber from each of said n chambers, valve means disposed in each of said n chambers for preventing the flow of material from said chambers to said passage means, valve actuating means disposed in said rear portion and coupling means extending from said valve actuating means in the rear portion to said forward portion through said cavity to selectively open and close the valve means whereby selective ones of said n chambers are connected to said spray chamber.

2. The spray gun of claim 1 wherein said valve means in the forward portion comprises a needle valve in each chamber sealing the passage therefrom, said valve coupling means constituting the stems of said needle valves extending between said forward and rear portions, said rear portion including n sets of bores each being aligned with one of said n chambers, said valve actuating means including a'piston connected to the end of said needle valve stem disposed in said rear portion, means including an inlet opening in said rear portion leading to each of said bores for coupling a source of fluid under pressure thereto to force said pistons in one direction and spring means adapted to bias said pistons in an opposite direction to open and close the needle valve.

3. The spray gun of claim 1, wherein n is two.

4. A method of quickly changing the material being sprayed in a multimaterial spray coating system, including at leastone spray gun having n chambers each having inlet and outlet means, a common discharge nozzle having a spray passage therethrough, means coupling the spray passage to each of said chambers and valve means for selectively opening and closing the coupling means whereby selective ones of said n chambers are coupled to the spray passage, comprising, circulating under pressure. materials from n sources of material continuously through the inlet and outlet means of different ones of the n chambers of said spray gun, preventing the passage of material being circulated through n-l chambers to said spray nozzle, allowing some of the circulating material from the remaining one of the n chambers to pass through said spray nozzle and then actuating said valve means preventing the passage of material from said previously used one of said n chambers and allowing some of the circulating material from another one of said ri chambers to pass through said spray nozzle.

5. The method of claim 4, wherein at least one of the a different material is circulated through the clean chamber during the operation of the spray gun with material from another of said chambers. 

1. In a multimaterial spray gun for use with n sources containing respective different ones of n materials, the combination comprising, a body including a forward portion and a rear portion with a cavity defined therebetween, said forward portion having n chambers, means including an inlet and an outlet port in said forward portion leading to each of said chambers for connecting said chambers with respective ones of said sources so that said chambers receive a substantially continuous circulating stream of respective different ones of said n preselected materials therethrough, a common discharge nozzle in said forward portion having a spray chamber therethrough, passage means leading to said spray chamber from each of said n chambers, valve means disposed in each of said n chambers for preventing the flow of material from said chambers to said passage means, valve actuating means disposed in said rear portion and coupling means extending from said valve actuating means in the rear portion to said forward portion through said cavity to selectively open and close the valve means whereby selective ones of said n chambers are connected to said spray chamber.
 2. The spray gun of claim 1 wherein said valve means in the forward portion comprises a needle valve in each chamber sealing the passage therefrom, said valve coupling means constituting the stems of said needle valves extending between said forward and rear portions, said rear portion including n sets of bores each being aligned with one of said n chambers, said valve actuating means including a piston connected to the end of said needle valve stem disposed in said rear portion, means including an inlet opening in said rear portion leading to each of said bores for coupling a source of fluid under pressure thereto to force said pistons in one direction and spring means adapted to bias said pistons in an opposite direction to open and close the needle valve.
 3. The spray gun of claim 1, wherein n is two.
 4. A method of quickly changing the material being sprayed in a multimaterial spray coating system, including at least one spray gun having n chambers each having inlet and outlet means, a common discharge nozzle having a spray passage therethrough, means coupling the spray passage to each of said chambers and valve means for selectively opening and closing the coupling means whereby selective ones of said n chambers are coupled to the spray passage, comprising, circulating under pressure materials from n sources of material continuously through the inlet and outlet means of different ones of the n chambers of said spray gun, preventing the passage of material being circulated through n- 1 chambers to said spray nozzle, allowing some of the circulating material from the remaining one of the n chambers to pass through said spray nozzle and then actuating said valve means preventing the passage of material from said previously used one of said n chambers and allowing some of the circulating material from another one of said n chambers to pass through said spray nozzle.
 5. The method of claim 4, wherein at least one of the materials that have been prevented from being sprayed is replaced by a solvent for the respective material which is circulated through the said n chambers so that a different material can be thereafter circulated through the cleaned chamber.
 6. The method of claim 5 wherein said one chamber of the spray gun is cleaned with solvent circulating therethrough and a different material is circulated through the clean chamber during the operation of the spray gun with material from another of said chambers. 